Ceramic membranes: Applications & benefits - From "A" to "Z"

Ceramic membranes are increasingly being used in a broad range of industries such as biotechnology & pharmaceutical, dairy, food & beverage, as well as chemical & petrochemical, microelectronics, metal finishing, and power generation. Each industry presents specific needs and opportunities. Within the food & beverage industry, some example applications are fruit juice clarification, cane sugar juice filtration, and spent (used) caustic or acid recovery. Thanks to their unique thermal, chemical, and mechanical properties, ceramic membranes offer significant advantages over polymeric membranes, stainless steel membranes, and conventional filtration techniques (e.g. rotary drum filtration, decantation, centrifugation, and media filtration) in many applications. Ceramic membranes are operated in the crossflow filtration mode, which has the benefit of maintaining a high filtration rate for membrane filters compared to the dead-end or direct-flow filtration mode of conventional filters. The ceramic membranes under discussion are constructed from multiple ceramic layers and formed into an asymmetric, multichannel element. The membrane elements are grouped within housings, and these membrane modules can withstand elevated temperatures (up to 300°C/570°F), extremes of pH (0 to 14), high operating pressures (up to 10 bar/145 psi) - making them suitable for many applications where polymeric and other inorganic membranes cannot be used. Several membrane pore sizes are available to suit the specific filtration needs - in the microfiltration, ultrafiltration and 'tight' ultrafiltration (or 'loose' nanofiltration) ranges - from 5 microns down to 1000 Daltons (MWCO). These membranes can be backpulsed (backpulse is a permeate flow reversal technique to reduce fouling and increase filtration efficiency), steam sterilized and chemically cleaned in-place, with increased process reliability and ease of automation. The remarkable physical and chemical stability of ceramic membranes allows reproducible performance over long lifetimes, which is well proven in numerous industrial installations. The paper will present examples demonstrating the ability of ceramic membranes to concentrate process streams, recover valuable products, and increase yields, making them a cost-effective and preferred method of filtration.